Printer ribbon cartridges for high speed printers are typically used with impact printers such as dot matrix printers, which cause extensive and rapid wear of the ribbon. These cartridges typically have an endless ribbon that is continuously inked. The ink is fed by gravity and capillary action from an inkwell or reservoir containing a hard felt mat through a felt wick to a brush that presses against a roller wheel used to advance the ribbon. The felt mat of these prior art reservoirs is usually a fairly hard and dense woolen mat.
It has been found that such prior art printer cartridges are unsatisfactory in several respects. The first problem with the prior art cartridges is that the ink reservoir has been subject to leakage in shipment, as temperature and pressure changes, or upending of the reservoir, can cause sufficient ink to leak from the reservoir so that it is nearly useless. Where pressure or temperature changes occur, ink may be forced out of the cartridge through the felt wick. The second problem with the prior art cartridges is inconsistent print quality over the life of the cartridge. The print quality of prior art cartridges often begins to deteriorate after as little as several hours of continuous use, and continues deteriorating over the next several hours until the print becomes unreadable. This deterioration in print quality is attributable to wear of the ribbon, which becomes less capable of absorbing and transmitting ink as it wears. In addition, the ink suspended in the felt mat of the prior art reservoirs becomes more and more difficult to extract from the mat as the amount of ink in the reservoir decreases, causing uneven print quality.
Accordingly, it would be desirable to provide a printer cartridge that has a leak resistant reservoir, and that has a consistent print quality throughout its operating life.